This invention is directed to an article molded from a blend of a poly(aryl ether ketone) and a poly(aryl ether sulfone).
Poly(aryl ether ketones) are crystalline polymers. They offer many property advantages which include solvent resistance, excellent wear and abrasion resistance, and excellent environmental stress crack resistance. Crystallization, however, causes a specific property deficiency in applications involved with replicating a mold surface, contour, or volume. Under certain conditions (e.g. injection molding), crystalline polymers exhibit high warpage. This is at least partially due to the high shrinkage of crystalline polymers (relative to amorphous polymers) and the problem of non-uniform shrinkage. This problem is compounded when the crystalline poly(aryl ether ketone) is annealed above its glass transition temperature. The applications where shrinkage and warpage minimization is highly desired include electrical connectors, bearings, sleeves, high tolerance applications, long injection molded parts, etc.
The requirements for a polymeric additive that will reduce the warpage and shrinkage problems for poly(aryl ether ketones) would include the following characteristics:
(1) Thermal stability is required at poly(aryl ether ketone) processing temperatures (minimum of 40.degree. C. above the poly(aryl ether ketone) crystalline melting point. This requires a polymeric additive which must be stable at 380.degree. C. and higher and exceeding 420.degree. C. for injection molding conditions. This requirement eliminates almost all polymer classes.
(2) Another key requirement is that phase separation occurs so that the crystallinity of poly(aryl ether ketones) can be retained during the molding cycle.
(3) The polymer additive should be amorphous so it would also not add to the shrinkage and warpage problems.
(4) The polymer additive should be thermoplastic and exhibit equal to lower melt viscosity than the poly(aryl ether ketone).
(5) The polymer additive should exhibit mechanical compatability with the poly(aryl ether ketone) such that at least additive strength and thoughness properties are achieved.
(6) The polymer additive should have a Tg of &gt;175.degree. C. so that a higher modulus above 150.degree. C. to at least 175.degree. C. can be achieved by the blend than the poly(aryl ether ketone) alone.
Of the many classes of polymers available, a class which would meet all of the requirements would be desirable and unique.
Blends of poly(aryl ether ketones) and poly(aryl ether sulfones) have been briefly alluded to in the patent literature. British Pat. No. 1,446,962 (page 3, lines 28 to 32) states:
"The aromatic polyether ketone may be blended with other thermoplastic polymeric substances, for example, polyesters, polyolefins, polyamides, polysulfones, and poly(vinyl chloride). The composition may be further mixed with particles; e.g., elastomeric materials and polytetrafluoroethylene." PA0 2,2-bis-(4-hydroxyphenyl)propane, PA0 2,4'-dihydroxydiphenylmethane, PA0 bis-(2-hydroxyphenyl)methane, PA0 bis-(4-hydroxyphenyl)methane, PA0 bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane, PA0 1,1-bis-(4-hydroxy-phenyl)ethane, PA0 1,2-bis-(4-hydroxyphenyl)ethane, PA0 1,1-bis-(4-hydroxy-2-chlorphenyl)ethane, PA0 1,1-bis-(3-methyl-4-hydroxyphenyl)propane, PA0 1,3-bis-(3-methyl-4-hydroxyphenyl)propane, PA0 2,2-bis-(3-phenyl-4-hydroxyphenyl)propane, PA0 2,2-bis-(3-isopropyl-4-hydroxyphenyl)propane, PA0 2,2-bis-(2-isopropyl-4-hydroxyphenyl)propane, PA0 2,2-bis-(4-hydroxy-naphthyl)propane, PA0 2,2-bis-(4-hydroxyphenyl)pentane, PA0 3,3-bis-(4-hydroxyphenyl)pentane, PA0 2,2-bis-(4-hydroxyphenyl)heptane, PA0 bis-(4-hydroxyphenyl)phenylmethane, PA0 2,2-(4-hydroxyphenyl)-1-phenyl-propane, PA0 2,2-bis-(4-hydroxyphenyl)1,1,1,3,3,3,-hexafluoropropane, and the like; PA0 di(hydroxyphenyl)sulfones such as bis-(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, 5-chloro-2,4'-dihydroxydiphenyl sulfone, 5'-chloro-4,4'-dihydroxydiphenyl sulfone, and the like; PA0 di(hydroxyphenyl)ethers such as bis-(4-hydroxyphenyl)ether, the 4,3'-, PA0 4,2'-2,2'-2,3-,dihydroxyphenyl ethers, PA0 4,4'-dihydroxyl-2,6-dimethyldiphenyl ether,bis-(4-hydroxy-3-isobutylphenyl)ether, PA0 bis-(4-hydroxy-3-isopropylphenyl)ether, PA0 bis-(4-hydroxy-3-chlorophenyl)ether, PA0 bis-(4-hydroxy-3-fluorophenyl)ether, PA0 bis-(4-hydroxy-3-bromophenyl)ether, PA0 bis-(4-hydroxynaphthyl)ether, PA0 bis-(4-hydroxy-3-chloronaphthyl)ether, and PA0 4,4'-dihydroxyl-3,6-dimethoxydiphenyl ether. PA0 2,2-bis(4-hydroxyphenyl)propane, PA0 bis(4-hydroxyphenyl)methane, PA0 4,4'-dihydroxydiphenyl sulfide, PA0 4,4'-dihydroxydiphenyl ether, PA0 4,4'-dihydroxydiphenyl sulfone, PA0 2,4'-dihydroxydiphenyl sulfone, PA0 4,4'-dichlorodiphenyl sulfone, PA0 4,4'-dinitrodiphenyl sulfone, PA0 4-chloro-4'-hydroxydiphenyl sulfone, PA0 4,4'-biphenol, hydroquinone, and the like. PA0 hydroquinone, PA0 4,4'-dihydroxybenzophenone, PA0 4,4'-dihydroxybiphenyl, and PA0 4,4'-dihydroxydiphenyl ether. PA0 4-(4-chlorobenzyl)phenol, PA0 4,4'-difluorobenzophenone, PA0 4,4'-dichlorobenzophenone, PA0 4-chloro-4'-fluorobenzophenone, ##STR32## PA0 (a) a mixture of substantially equimolar amounts of PA0 (b) at least one aromatic monoacyl halide of formula EQU H--Ar"--COW PA0 where --Ar"-- is a divalent aromatic radical and H is an aromatically bound hydrogen atom, Y is halogen, and COY is an aromatically bound acyl halide group, which monoacyl halide is self-polymerizable, and PA0 (c) a combination of (a) and (b) in the presence of a fluoroalkene sulphonic acid.
This disclosure generally describes blends of poly(aryl ether ketones) and poly(aryl ether sulfones). However, the above-quoted statement contains many inaccuracies. Blending poly(vinyl chloride) at temperatures &gt;300.degree. C. would give instantaneous degradation yielding large quantities of hydrochloric acid as well as other noxious by-products. Polyolefins, polyesters (e.g., poly(ethylene terephthalate, poly(butylene terephthalate) and polyamides (e.g., nylon 6, nylon 6,6, nylon 11, and nylon 12) also will severely degrade at processing temperature in excess of 300.degree. C. and thus produce useless blends with poly(aryl ether ketones).
U.S. Pat. No. 3,324,199 describes blends of a specific poly(aryl ketone) containing ortho hydroxy groups (relative to the ketone group). These materials are described as ultraviolet light stabilizers for a variety of polymers including polyethylene, polypropylene, poly(vinyl chloride), poly(vinylidene chloride), polyacrylic acid esters, polyacrylonitrile, polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyesters, polyamides, and polyimides. These poly(aryl ether ketones) are generally amorphous and require aromatic hydroxyls ortho to the main chain ketones. The poly(aryl ketones) of this invention are crystalline, have no ortho hydroxyls, and could not be blended with many of the above mentioned polymers as the melting point of the poly(aryl ether ketones) are higher than the degradation temperature of most of the above cited polymers.
U.S. Pat. No. 4,435,350 describes a method for the orientation of thermoplastic polyether ether ketone films. The patent states that the polyether ether ketone may be blended with other resins such as polyarylene polyether polysulfone for the purpose of improving the fluidity of the polyether ether ketone in extrusion processing. The examples in this patent describe extruding of the polyether ether ketone into films. This patent does not disclose or suggest that the polyether ether ketone alone or blended with another resin can be formed into molded articles.
One method which has been found to decrease this shrinkage and warpage problem is to add a high glass transition temperature (Tg), amorphous poly(aryl ether sulfone) to the crystalline poly(aryl ether ketone).